<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>demo 2-33</title>
	</head>
	<body>
	</body>
	<script>
		function calculate(method,...nums){
			let result;
			if(!method||nums.length == 0){
				alert('请传入参数！');
				return;
			}
			if(method == '*'){
				result = 1;
				for(let i = 0;i < nums.length;i++){
					result *=nums[i];
				}
			}else if(method == '+'){
				result = 0;
				for(let i = 0;i < nums.length;i++){
					result +=nums[i];
				}
			}
			alert(result);
		}	
		calculate("+",1,2);
		calculate("+",1,2,3,4,5);
		calculate("*",1,2,3);
		calculate("*",1,2,3,4,5);
	</script>
</html>